Flame-retardant moulded component

ABSTRACT

A flame-retardant molded component comprises a matrix-forming polymer material. The component also comprises 5 to 20 wt % of melamine cyanurate and 3 to 10 wt % of a polyphosphonate.

This invention is concerned with a flame-retardant molded component. Theinvention is particularly applicable to monofilaments for formation intobraided sleeves used to protect electrical wires or pipes.

It is well-known to form molded components from polymers such as nylon6. For example, braided sleeves used for protecting wires or pipes fromabrasion damage, for example in an engine compartment of a vehicle, areoften formed from monofilaments of nylon 6. The monofilaments have adiameter of about 0.25 mm to about 3.25 mm.

It is also well-known to provide polyamides, eg nylon 6 or nylon 66, orother polymers with flame-retardancy properties by filling them withflame-retardant materials. Typical applications include moldedcontainers for electrical equipment and coatings for electrical wires.Melamine cyanurate is a known flame-retardant filler for use inpolyamides for such applications. In the event of fire, the melaminecyanurate decomposes giving off flame-retardant gases. However, as theproportion of melamine cyanurate increases, the flexibility and surfacequality of the material decreases making the material prone to cracking.For this reason, providing sufficient melamine cyanurate for therequired flame-retardancy renders the material unsuitable for many uses,for example for forming into the above-mentioned monofilaments. For thisreason, the protective sleeves referred to above are not formed fromflame-retardant monofilaments despite the obvious fire risks present inengine compartments.

Polyphosphonates are known as flame-retardant fillers in some polymericmatrices. However, they are not effective enough, when used alone, toenable a molded component to pass flame-retardancy tests.

It is an object of the present invention to provide a flame-retardantmolded component which combines good flame-retardancy properties withgood flexibility and good surface quality.

The invention provides a flame-retardant molded component comprising amatrix-forming polymer material, characterised in that the componentalso comprises 5 to 20 wt % of melamine cyanurate, and 3-10 wt % of apolyphosphonate.

In a component according to the invention, it is found that the presenceof both melamine cyanurate and a polyphosphonate enables a greaterproportion of melamine cyanurate to be included before the flexibilityand surface quality become unacceptable. Furthermore, since, thepolyphosphonate itself has flame-retardancy properties, the quantity ofmelamine cyanurate required is reduced. The polyphosphonate also acts asa plasticiser improving the mechanical properties of the component andassisting the dispersion of the melamine cyanurate. In particular, it isfound that the component can be molded in the form of a successfulflame-retardant monofilament.

Preferably, the quantity of polyphosphonate is 3-10 wt %.

The matrix of a component according to the invention is, preferably,formed from nylon 6 but nylon 12 or 66 are also possible. Also possibleare poly (ethylene terephthalate) and poly (ethylene naphthalate).

The polyphosphonate is preferably an organo polyphosphate called AmguardP45 and obtainable from Albright & Wilson.

There now follows a detailed description of an example which isillustrative of the invention.

In the example, 85 wt % of nylon 6 was compounded with 10 wt % ofmelamine cyanurate, in the form of particles averaging 10 microns indiameter, and with 5 wt % of Amguard P45. The mixture was extruded as amonofilament having a diameter of 3.25 mm. This monofilament was braidedinto a protective sleeve in a conventional manner.

The sleeve achieved the UL1441 VW-1 requirements for electrical sleevingand passed the UL94 Vo standard for flame retardancy at 0.8 mmthickness. The monofilaments had good flexibility and surface quality.

What is claimed is:
 1. A flame-retardant nylon monofilament formed by aprocess comprising the steps of: compounding a mixture consistingessentially of 5 to 20 weight percent melamine cyanurate and 3 to 10weight percent of an organopolyphosphonate, with the balance being apolymer selected from the group consisting of Nylon 6, Nylon 12 andNylon 66; and extruding as a monofilament said compounded mixture. 2.The flame retardant nylon monofilament of claim 1, comprising from 5 to15 weight percent of melamine cyanurate.
 3. The flame retardant nylonmonofilament of claim 2, comprising 10 weight percent of melaminecyanurate and 5 weight percent of organopolyphosphonate.
 4. The flameretardant monofilament of claim 1, wherein said polymer is Nylon 6.